Field of the Invention
The present invention relates generally to an electronic audio processing system and method, and more particularly to a component for insertion into the line prior to power amplification and a related method which component and method render a frequency response in which undesirably strong frequency bands are flattened relative to the total frequency response by up to 10 dB, thereby providing enhanced dynamic audio reproduction.
Electronic audio reproduction systems include as a minimum an audio signal source, an amplifier (typically including a preamplifier and a power amplifier), and speakers or headphones. The sound of even basic systems usually has at least bass and treble adjustments to vary the tone of the reproduced audio. The art has provided more variety to these basic controls of tone over time, with the enhanced controls manifesting themselves in two completely different techniques.
The first technique is merely an enhancement of the simple bass and treble controls. This approach is embodied in the graphic equalizer, which provides between five and twenty-seven (or more) frequency band adjustments to the audio signal. A twenty-seven band equalizer is a 1/3 octave device, and 1/6 octave equalizers do exist which would have more than twenty-seven frequency bands.
An equalizer splits the audio signal into different frequencies, each of which can be individually attenuated or boosted. Such equalizers are thus completely static in their adjustments, since the attenuation and boost settings of the various frequency bands are manually set at desired levels, and remain there until they are manually reset.
The second technique is that of dynamic amplitude expansion, in which low level or soft sounds (of all frequencies) are slightly boosted, high level or loud sounds are slightly attenuated, and mid level or average sounds are neither attenuated nor boosted. Such dynamic amplitude expansion thus provides a greater variation of amplitude, which may be desirable when listening to music where the overall variation in amplitude has been reduced in the recording process to ensure better reproduction. Typically, very low levels are boosted in the recording process to provide a better signal-to-noise level.
However, neither of these two techniques are capable of providing a truly dynamic reproduction of audio due to limitations inherent in their design. The first technique is static rather than dynamic, and thus as the signal changes, the equalizer is completely nonresponsive. This can require frequent adjustments, particularly as the source or the type of music is varied. The second technique is completely ineffective at varying the relative response of different frequency bands, and thus is not of interest herein.
The problem which these prior art devices and techniques do not address is that different audio sources and types of music have different frequency problems therein. For example, while CD's and digitally recorded music are apt to be nearly completely flat in overall response (subject to proper microphone placement and sound recording), overall frequency response of music from tapes and records and music recorded with poor microphone placement or poor recording equipment is anything but flat. Even more unfortunately, the non-flat frequency response is apt to be unpredictable and to vary widely with different sources and types of music, or even with different recordings of the same type of music from the same source.
It is accordingly the primary objective of the present invention that it provide an accurate reproduction system and a related methodology for operating the system to compensate for the wide variations in frequency response in any audio signal in recorded or live music. It is a further objective that the system of the present invention and the methodology for operating the system of the present invention also provide such compensation on a dynamic basis, automatically correcting frequency response irregularities as the audio signal is being reproduced. As such, the system of the present invention and the methodology for operating the system of the present invention must provide accurate dynamic compensation without the necessity for the user making frequent or complicated adjustments.
It is a further objective of the accurate reproduction system of the present invention and the related methodology for operating the system of the present invention that they provide for some degree of adjustment to compensate for sources which have a greater or lesser inaccuracy in their frequency response. This adjustment to compensate for variations in the frequency response must be easy for the user to accomplish. In addition, manual adjustment of the degree of correction to flatten overall frequency response should be facilitated by providing an indicator of the degree of adjustment made by the user which is visible as the adjustment is being made.
The accurate reproduction system of the present invention must also be of a design which is both durable and long lasting, and it should also require little or no calibration or other maintenance to be provided by the user. In order to enhance the market appeal of the accurate reproduction system of the present invention, it should also be of inexpensive construction to thereby afford it the broadest possible market. Finally, it is also an objective that all of the aforesaid advantages and objectives of the accurate reproduction system of the present invention and the related methodology for operating the system of the present invention be achieved without incurring any substantial relative disadvantage.